P. Scheid

Synteny and candidate gene prediction using an anchored linkage map of Astyanax mexicanus

The blind Mexican cave tetra, Astyanax mexicanus, is a unique model system for the study of parallelism and the evolution of cave-adapted traits. Understanding the genetic basis for these traits has recently become feasible thanks to production of a genome-wide linkage map and quantitative trait association analyses. The selection of suitable candidate genes controlling quantitative traits remains challenging, however, in the absence of a physical genome. Here, we describe the integration of multiple linkage maps generated in four separate crosses between surface, cave, and hybrid forms of A. mexicanus. We performed exhaustive BLAST analyses of genomic markers populating this integrated map against sequenced genomes of numerous taxa, ranging from yeast to amniotes. We found the largest number of identified sequences (228), with the most expect (E) values <10−5 (95), in the zebrafish Danio rerio. The most significant hits were assembled into an “anchored” linkage map with Danio, revealing numerous regions of conserved synteny, many of which are shared across critical regions of identified quantitative trait loci (QTL). Using this anchored map, we predicted the positions of 21 test genes on the integrated linkage map and verified that 18 of these are found in locations homologous to their chromosomal positions in D. rerio. The anchored map allowed the identification of four candidate genes for QTL relating to rib number and eye size. The map we have generated will greatly accelerate the production of viable lists of additional candidate genes involved in the development and evolution of cave-specific traits in A. mexicanus.

Genetic Indicators of Drug Resistance in the Highly Repetitive Genome of Trichomonas vaginalis

Abstract Trichomonas vaginalis, the most common nonviral sexually transmitted parasite, causes ∼283 million trichomoniasis infections annually and is associated with pregnancy complications and increased risk of HIV-1 acquisition. The antimicrobial drug metronidazole is used for treatment, but in a fraction of clinical cases, the parasites can become resistant to this drug. We undertook sequencing of multiple clinical isolates and lab derived lines to identify genetic markers and mechanisms of metronidazole resistance. Reduced representation genome sequencing of ∼100 T. vaginalis clinical isolates identified 3,923 SNP markers and presence of a bipartite population structure. Linkage disequilibrium was found to decay rapidly, suggesting genome-wide recombination and the feasibility of genetic association studies in the parasite. We identified 72 SNPs associated with metronidazole resistance, and a comparison of SNPs within several lab-derived resistant lines revealed an overlap with the clinically resistant isolates. We identified SNPs in genes for which no function has yet been assigned, as well as in functionally-characterized genes relevant to drug resistance (e.g., pyruvate:ferredoxin oxidoreductase). Transcription profiles of resistant strains showed common changes in genes involved in drug activation (e.g., flavin reductase), accumulation (e.g., multidrug resistance pump), and detoxification (e.g., nitroreductase). Finally, we identified convergent genetic changes in lab-derived resistant lines of Tritrichomonas foetus, a distantly related species that causes venereal disease in cattle. Shared genetic changes within and between T. vaginalis and Tr. foetus parasites suggest conservation of the pathways through which adaptation has occurred. These findings extend our knowledge of drug resistance in the parasite, providing a panel of markers that can be used as a diagnostic tool.

Filthy lucre: A metagenomic pilot study of microbes found on circulating currency in New York City

Background Paper currency by its very nature is frequently transferred from one person to another and represents an important medium for human contact with—and potential exchange of—microbes. In this pilot study, we swabbed circulating

Genetic indicators of drug resistance in the highly repetitive genomes of Trichomonas vaginalis and other trichomonads

1 bills obtained from a New York City bank in February (Winter) and June (Summer) 2013 and used shotgun metagenomic sequencing to profile the communities found on their surface. Using basic culture conditions, we also tested whether viable microbes could be recovered from bills. Results Shotgun metagenomics identified eukaryotes as the most abundant sequences on money, followed by bacteria, viruses and archaea. Eukaryotic assemblages were dominated by human, other metazoan and fungal taxa. The currency investigated harbored a diverse microbial population that was dominated by human skin and oral commensals, including Propionibacterium acnes, Staphylococcus epidermidis and Micrococcus luteus. Other taxa detected not associated with humans included Lactococcus lactis and Streptococcus thermophilus, microbes typically associated with dairy production and fermentation. Culturing results indicated that viable microbes can be isolated from paper currency. Conclusions We conducted the first metagenomic characterization of the surface of paper money in the United States, establishing a baseline for microbes found on

Gene Networks in Development and Evolution Special Feature Sackler Colloquium: Synteny and candidate gene prediction using an anchored linkage map of Astyanax mexicanus

1 bills circulating in New York City. Our results suggest that money amalgamates DNA from sources inhabiting the human microbiome, food, and other environmental inputs, some of which can be recovered as viable organisms. These monetary communities may be maintained through contact with human skin, and DNA obtained from money may provide a record of human behavior and health. Understanding these microbial profiles is especially relevant to public health as money could potentially mediate interpersonal transfer of microbes.

Managing and Analyzing Big-Data in Genomics

Background Trichomonas vaginalis, the most common non-viral sexually transmitted parasite, causes ~283 million trichomoniasis infections annually and is associated with complications during pregnancy and increased risk of HIV-1 acquisition. The antimicrobial drug metronidazole is used for treatment, but has lead to widespread drug resistance. We undertook sequencing of multiple clinical isolates and lab derived lines to identify genetic markers and mechanisms of metronidazole resistance. Results Reduced representation genome sequencings of more than 100 T. vaginalis clinical isolates identified 3,923 SNP markers and presence of a bipartite population structure. Linkage disequilibrium decays rapidly, suggesting genome-wide recombination and the feasibility of genetic association studies in the parasite. We identified 72 SNPs associated with metronidazole resistance, and a comparison of SNPs within several lab-derived resistant lines revealed an overlap with the clinically resistant isolates. We identified SNPs in sets of genes for which no function has yet been assigned, as well as in functionally-characterized genes highly relevant to drug resistance (e.g., pyruvate:ferredoxin oxidoreductase (PFO)). Transcription profiling of these and other genes served as proxy for testing the functional consequences of multiple identified SNPs. Transcription profiles of lab-derived drug resistance strain as well as clinically resistant strain depict common regulation changes in carbohydrate metabolism and oxygen detoxification pathways correlated with Mz resistance. Finally, we identified convergent genetic changes in lab-derived resistant lines of Tritrichomonas foetus, a distantly-related species that causes venereal disease in cattle. Conclusions Our observation of shared genetic changes within and between T. vaginalis and Tr. foetus parasites suggests conservation of the pathways through which adaptation has occurred. These findings extend our knowledge of drug resistance in the parasite, providing a panel of markers that can be used as a diagnostic tool.